If your clutch pedal feels spongy and will not fully engage or disengage the disc, you probably need to bleed the system. Bleeding the clutch takes two people, so enlist the help of a friend when you attempt the job. Also keep an owner's manual handy, as you must locate the slave cylinder for the clutch before you can bleed it.
Refer to the vehicle owner's manual to locate the clutch slave cylinder, which will have a screw (usually 8 mm) that releases pressure from the system. Known as the bleeder screw or bleeder valve, it is key to bleeding the system and helps maintain the hydraulic pressure with everyday use.
Have your project partner sit in the car and push the clutch pedal all the way down. Loosen the bleeder screw with an end wrench or socket, and use a thick rag or container such as a coffee can to catch excess fluid. A bunch of air will probably come out first, mixed with a tiny bit of fluid. Make sure the master cylinder has fluid in it at all times--if air enters the lines, you will have to bleed the system again.
Re-tighten the bleeder screw, then tell your project partner to slowly let up on the clutch pedal until it is free-standing.
Have your project partner push the clutch to the floor. Loosen the bleeder screw. Repeat these steps until only fluid--not air--comes out of the slave cylinder bleeder valve.
Tighten the bleeder screw a final time and fill the master cylinder with hydraulic fluid.
